This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-138510, filed May 19, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a flat display apparatus and a method of manufacturing the same, and more particularly to a flat display apparatus incorporating spacers for maintaining a predetermined distance between substrate thereof and a method of manufacturing the same.
Flat display apparatuses represented by liquid crystal display apparatuses having advantages of small thickness, light weight and small power consumption are widely used in a variety of industrial fields.
For example, an active-matrix liquid crystal display apparatus incorporates an array substrate; a counter substrate disposed opposite to the array substrate; a liquid crystal layer held between a pair of the substrates and serving as a light modulation layer; and a sealing-material portion disposed between the pair of the substrates and formed into a frame-like shape around the light modulation layer.
In order to maintain satisfactory display quality in the flat display apparatus of the foregoing type, a predetermined gap must be maintained between the pair of the substrates. Therefore, an attempt has been made in recent years as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-148836 such that spacer is integrally formed with either of the array substrate or the counter substrate. According to the foregoing disclosure, a structure has been disclosed in which the spacer is formed in the sealing-material pattern integrally with the substrate in the sealing-material portion.
FIG. 9 shows a sealing-material portion 202 of a conventional liquid crystal display apparatus and prism-like spacers 201 disposed in the sealing-material portion 202 to maintain a predetermined gap between a pair of substrates.
In a step of applying a sealing material, the prism-like spacers 201 are disposed outside the region which is coated with the sealing material. The sealing material is spread in its widthwise direction owing to the pressure applied in the sealing step. At this time, the prism-like spacers 201 are enclosed by the spread sealing-material portion 202. The spread of the sealing material caused in the sealing step is inhibited by the prism-like spacers 201. Therefore, an air bubble 299 is sometimes formed adjacent to the side wall of the prism-like spacer 201 at a downstream position in the direction in which the sealing material is spread, as shown in FIG. 9. The foregoing air bubble 299 causes the shape of the sealing-material portion 202 to deteriorate. Thus, interruption of the formed seal sometimes occurs.
Specifically, the air bubble 299 formed in the sealing-material portion 202 reduces the width of the sealing-material portion 202, causing the resistance against environment and reliability to deteriorate. When the inside portion of each liquid crystal cell is exhausted to produce a vacuum in the inside portion in a vacuum annealing step or the step of injecting liquid crystal, air in the air bubble 299 is expanded, thus, there is a problem that separation of the seal takes place. In a case where the shape of the sealing-material portion 202 deteriorates, undesired cut surface is formed in a direction of the thickness of the substrate when the substrate is scribed. As a result, there arises a problem in that the manufacturing yield deteriorates.
To overcome the foregoing problems, an object of the present invention is to provide a flat display apparatus incorporating spacers formed integrally with at least either substrate to maintain a predetermined distance between the substrates, capable of preventing formation of an air bubble in a sealing-material portion and excellent in the reliability and manufacturing yield and a method of manufacturing the same.
Another object of the present invention is to provide a flat display apparatus which can quickly be manufactured and a method of manufacturing the same.
According to one aspect of the invention, there is provided a flat display apparatus incorporating a first substrate; a second substrate disposed opposite to and apart from the first substrate for a predetermined gap; a sealing material disposed between the first and second substrates and formed into a frame-like shape to bond the first and second substrates to each other; a light modulation layer held in a gap between the first and second substrates bonded to each other with the sealing material; and spacers secured integrally with at least either of the first and second substrates to maintain the gap, wherein a portion of the spacers is disposed in the sealing material and another portion of the spacers projects from the sealing material.
According to another aspect of the invention, there is provided a method of manufacturing a flat display apparatus incorporating first and second substrates, a light modulation layer disposed between the substrates, a sealing material disposed between the substrates and formed into a frame-like shape enclosing the light modulation layer and spacers provided integrally with the first substrate to maintain a predetermined gap between the first and second substrates, the method of manufacturing a flat display apparatus comprising the steps of: providing the spacers for the first substrate; coating either of the first substrate or the second substrate with a sealing material; overlaying the first and second substrates through the sealing material and the spacers; and pressing the first and second substrates to harden the sealing material to form the sealing-material portion and forming a portion of the spacers in the sealing-material portion and another portion to project from the sealing-material portion.
According to the present invention, a portion of the spacers which is in contact with the sealing-material portion is disposed in the sealing-material portion and the other portion projects from the sealing-material portion. Therefore, formation of an air bubble in the sealing-material portion can considerably be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.